Aroma retention in sol-gel-made silica particles.

The retention performance of aroma molecules from different chemical classes (e.g., alcohols, esters, aldehydes, and terpenes) by silica particles made by hydrolysis of tetraethyl orthosilicate is investigated. Since particle morphology, porosity, and pore size distribution can be controlled by the sol-gel preparation method, the influence of the nanoconfinement in the microporous matrix on aroma retention is studied as well as the effect of the initial aroma load of the particles. As the porosity is decreased, aroma molecules are entrapped more efficiently in the silica particles. The retention performance decreased from alcohols > aldehydes >/= esters > terpenes as with polar organic matrices. Open sol-gel-made silica particles show an increased retention with increasing aroma load, while denser silica matrices show a maximum retention with increasing load.